Java swing 布局没有达到我想要的效果

Question

我正在尝试编写我认为应该易于指定的对话框，我有一些标签和它们对面的一些文本区域，然后是“确定”和“取消”按钮。 在中间，我有一个宽组件（例如，我使用了标签）

 |label|  [combo box]
 |label|  [txtfield]
 |label|  [txtfield]
 |  long label here |


 [btn1]      [btn2]

，我正在尝试使用 GridBagLayout，它没有做我想要的事情，我不确定我明白为什么。基本上我希望按钮固定在对话框的底部。

下面的代码说明了我如何使用它：

package gui;

import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;

import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextArea;

public class GridBagLayoutExample2 extends JFrame {

    private static final long serialVersionUID = -1972347726217162551L;
    final private JLabel lbl1 = new JLabel("LABEL1: ");
    final private JLabel lbl2 = new JLabel("LABEL2: ");
    final private JLabel lbl3 = new JLabel("LABEL3: ");
    final private JTextArea txt1 = new JTextArea(" ");
    final private JComboBox cmb1 = new JComboBox();
    final private JTextArea txt2 = new JTextArea("");
    final private JLabel lblLine = new JLabel("a compenent on all the line");
    final private JButton btnOK = new JButton("OK");
    final private JButton btnCancel = new JButton("Cancel");

    public GridBagLayoutExample2() {

        GridBagLayout bl = new GridBagLayout();
        Container pane = getContentPane();
        pane.setLayout(bl);
        GridBagConstraints c = new GridBagConstraints();
        int r = 0;

        placeComponentInGridBagLayout(lbl1, pane, bl, c, 0, r, null, null, GridBagConstraints.WEST, GridBagConstraints.HORIZONTAL, null, null, null, null);
        placeComponentInGridBagLayout(cmb1, pane, bl, c, 1, r++, null, null, GridBagConstraints.EAST, GridBagConstraints.HORIZONTAL, null, null, null, null);
        placeComponentInGridBagLayout(lbl2, pane, bl, c, 0, r, null, null, GridBagConstraints.WEST, GridBagConstraints.HORIZONTAL, null, null, null, null);
        placeComponentInGridBagLayout(txt2, pane, bl, c, 1, r++, null, null, GridBagConstraints.EAST, GridBagConstraints.HORIZONTAL, null, null, null, null);
        placeComponentInGridBagLayout(lbl3, pane, bl, c, 0, r, null, null, GridBagConstraints.EAST, GridBagConstraints.HORIZONTAL, null, null, null, null);
        placeComponentInGridBagLayout(txt1, pane, bl, c, 1, r++, null, null, GridBagConstraints.EAST, GridBagConstraints.HORIZONTAL, null, null, null, null);
        placeComponentInGridBagLayout(lblLine, pane, bl, c, 0, r++, null, null, GridBagConstraints.WEST, GridBagConstraints.HORIZONTAL, 2, null, null, null);
        placeComponentInGridBagLayout(btnOK, pane, bl, c, 0, null, null, null, GridBagConstraints.PAGE_END, GridBagConstraints.HORIZONTAL, null, null, null, null);
        placeComponentInGridBagLayout(btnCancel, pane, bl, c, 1, null, null, null, GridBagConstraints.PAGE_END, GridBagConstraints.HORIZONTAL, null, null, null, null);

        setSize(new Dimension(850, 350));
        pack();
        setVisible(true);
    }

    public static void placeComponentInGridBagLayout(Component component, Container container, GridBagLayout bagLayout, GridBagConstraints c, Integer gridX, Integer gridY, Double weightX, Double weightY, Integer anchor, Integer fill, Integer ipadx, Integer ipady,
            Integer gridWidth, Integer gridHeight) {
        if (c == null) {
            c = new GridBagConstraints();
        }
        if (gridX != null) {
            c.gridx = gridX;
        }
        if (gridY != null) {
            c.gridy = gridY;
        }
        if (weightX != null) {
            c.weightx = weightX;
        }
        if (weightY != null) {
            c.weighty = weightY;
        }
        if (fill != null) {
            c.fill = fill;
        }
        if (anchor != null) {
            c.anchor = anchor;
        }
        if (ipadx != null) {
            c.ipadx = ipadx;
        }
        if (ipady != null) {
            c.ipady = ipady;
        }
        if (gridWidth != null) {
            c.gridwidth = gridWidth;
        }
        if (gridHeight != null) {
            c.gridheight = gridHeight;
        }
        bagLayout.setConstraints(component, c);

        container.add(component);
    }

}

知道我做错了什么吗？ Swing 中是否有更现代的方法来实现相同的目标？

谢谢

Answer 1

当做一个简单的表单时， SpringLayout 是一个有用的布局管理器。要将组件打包在一行上，使用 BoxLayout。

这是一个简单的示例：

这是代码：

public class LayoutDemo extends JFrame {

    public LayoutDemo() {

        JLabel label1 = new JLabel("label 1");
        JLabel label2 = new JLabel("label 2");
        JLabel label3 = new JLabel("label 3");
        JComboBox<String> combobox = new JComboBox<>();
        JTextField field1 = new JTextField();
        JTextField field2 = new JTextField();

        JPanel formPanel = new JPanel(new SpringLayout());
        formPanel.add(label1);
        formPanel.add(combobox);
        formPanel.add(label2);
        formPanel.add(field1);
        formPanel.add(label3);
        formPanel.add(field2);

        SpringUtilities.makeCompactGrid(formPanel, 3, 2, 2, 2, 3, 3);

        JLabel longLabel = new JLabel("This is a longer label");
        longLabel.setAlignmentX(CENTER_ALIGNMENT);

        JButton button1 = new JButton("Button 1");
        JButton button2 = new JButton("Button 2");

        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout(new BoxLayout(buttonPanel, BoxLayout.LINE_AXIS));
        buttonPanel.add(button1);
        buttonPanel.add(Box.createHorizontalGlue());
        buttonPanel.add(button2);

        JPanel basePanel = new JPanel();
        basePanel.setLayout(new BoxLayout(basePanel, BoxLayout.PAGE_AXIS));
        basePanel.add(formPanel);
        basePanel.add(longLabel);

        add(basePanel, BorderLayout.NORTH);
        add(buttonPanel, BorderLayout.SOUTH);
        pack();
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setVisible(true);
    }

    public static void main(String[] args) {
        new LayoutDemo();
    }
}

您可能想要使用 BorderLayout 例如将 formPanel 保持在顶部而不拉伸时调整窗口大小。但我希望我给了你一些关于如何将 SpringLayout 用于表单的想法。

Answer 2

我发现的一个问题是，您的长标签与“确定”按钮位于同一网格单元格中。
如果您希望按钮锚定在整个对话框的底部，请尝试使用 BorderLayout。为按钮创建一个单独的面板并将其放入 BorderLayout.SOUTH 中。然后使用 GridBagLayout 将主要内容放入另一个面板中，并将其放入 BorderLayout.CENTER 中。这些按钮不会与您的文本组件完美对齐，但我认为没关系。

Answer 3

您可以使用 borderlayout 和 gridlayout 的组合，如下所示

package sof;

import java.awt.BorderLayout;
import java.awt.GridLayout;

import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class CustomLayoutFrame{
    public static void main(String args[]) {
        JFrame frame = new JFrame("Custom Layout Frame");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(new BorderLayout());
        JPanel centerPnl = new JPanel();
        centerPnl.setLayout(new BorderLayout());
        JPanel gridLayoutPane = new JPanel(); 
        GridLayout gridLayout = new GridLayout(3,2);
        gridLayoutPane.setLayout(gridLayout);
        gridLayoutPane.add(new JLabel("Label1"));
        gridLayoutPane.add(new JComboBox());
        gridLayoutPane.add(new JLabel("Label2"));
        gridLayoutPane.add(new JTextField());
        gridLayoutPane.add(new JLabel("Label3"));
        gridLayoutPane.add(new JTextField());
        centerPnl.add(gridLayoutPane, BorderLayout.CENTER);
        centerPnl.add(new JLabel("Long label should be going here"), BorderLayout.SOUTH);

        frame.add(centerPnl, BorderLayout.CENTER);

        JPanel bottomPanel = new JPanel();
        bottomPanel.add(new JButton("Button1"));
        bottomPanel.add(new JButton("Button2"));

        frame.add(bottomPanel, BorderLayout.SOUTH);

        frame.setSize(300, 150);
        frame.setVisible(true);
      }
}

Answer 4

用于这些目的的一个不错的 LayoutManager 是 FormLayout< /a> 来自 JGoodies。